Spinal cord injuries with consequent paralysis affect more than 250,000 people in the US and several million worldwide. The biological causes that prevent axonal regeneration to occur in the central nervous system (CMS) are still elusive. The lack of experimental techniques suited to address these questions in simple genetic model organisms has delayed the pace of the discoveries in this field. Recently, we have demonstrated that laser surgery can be used as a precise cutting tool to severe individual neurons in the nematode Caenorhabditis elegans. In the operated animals, the cut axons spontaneously regenerated with a complete recovery of the neuronal and behavioral function. Our first goal is to investigate in great detail the properties of femtosecond laser ablation of tissue and control its precision for severing axons inside C. elegans with minimal interference to the regeneration processes. The broad goal of this proposal is to understand the molecular mechanisms and the events that regulate axonal regeneration. We propose specifically to proceed as follow: 1. Determine the extent of tissue damage caused by the laser surgery and set optimal conditions for large scale screens. 2. Characterize and understand the dynamic events happening on the membrane at both sides of the severed axon. 3. Discover the genes and conditions that are essential for the regeneration process to occur. Hundred of thousands of people each year in the US and in the world are affected by paralisys caused by injuries or internal traumas of the nerves. The lacking ability of nerves in the Central Nervous System to regenerate is the main reason of the minimal recovery of the patients. The studies presented in this proposal will provide new insights into the fascinating process of nerve regeneration and hopefully offer new avenues for therapies. [unreadable] [unreadable]